Conventionally, in order to detect leaks in containers that hold liquids, such as tanks and metal-lined pits, liquid is first drained from the tank or metal-lined pit. After the liquid is drained out of the container, a bubble-forming solution is applied to a portion of the surface of the container that is to be inspected for flaws and a vacuum device is applied over the bubble-forming solution. The vacuum device includes a stiff, closed-cell foam seal for contacting the surface and forming a seal between the vacuum device and the surface. In order to form a vacuum chamber around the portion of the surface that is to be inspected, the worker has to manually push the vacuum device against the surface to be tested. If a leak is present in a liner material of the tank or metal-lined pit, air is drawn through the leak and a bubble forms in the vacuum chamber of the vacuum device. The vacuum device includes a viewing window that allows a worker to see if bubbles are forming in the vacuum chamber. Because of the stiff nature of the seal, the worker must force the vacuum device against the surface to compress the stiff, closed-cell foam seal and establish the vacuum. A force creating the vacuum may be generated by an air-driven Venturi. The vacuum may be initiated by opening an air flow valve that allows compressed air to flow through the Venturi. If a flaw is found, the worker marks the area with a suitable marking device, breaks the vacuum by closing the air flow valve and moves to the next area of the surface for leak detection.